A 40 kW. 400 V, 3-phase, 6-pole. 50 Hz wound rotor induction motor develops a maximum torque of 2.75 times full-load torque at a slip of 0.18 when operating at rated voltage and frequency with slip rings short-circuited. Stator resistance and rotational losses may be ignored. Determine:
(a) the full-load slip.
(b) the full-load rotor copper loss.
(c) the starting torque at half the rated voltage. The rotor circuit resistance is now doubled by adding an external resistance through the slip rings. Determine:
(d) the developed torque at full-load current.
(e) the slip in part (d).